I dont know how the opus shuts down your computer, but i guess it uses the same functionality as your acpi power button. Since the "auto-shutdown when power-button is pressed" function does not work with minlogon, try the program here minlogon -> "acpi power button can't shutdown" workaround

I want my via M10K to shutdown when i shutdown my car to, so i was wondering, how does your opus tell your pc to shutdown?

it has to do with the ACPI power button event not being captured by minlogon. someone posted an applet that fixed it in this forum. you'll have to search for it though because i can't remember where it is.

basically opus just waits 10 seconds (or you can set the jumpers to different times) before it "pushes the power button" and you just tell windows that when you push the power button to shut down your pc.